TU-85 BARGE - Powerplant
The engine is the heart of the plane, if it is successful, the future of the aircraft is assured. The 24-cylinder engines were based on ideas introduced before the war at the Moscow Aviation Institute under the direction of G.Skubacevskogo and V.Dobrynina.
This project represented in many ways the further development of the projects of the aircraft "80" in the direction of further improvement of the flight and tactical data using the same types of powerplants (engines Ash-2TK, VD-3TK, M-35, M-501, M-51, and VS-2). Gradually, during the design of the aircraft, the designers moved, in essence, to a completely new aircraft, since neither the aerodynamic characteristics, nor even the specific characteristics of the power plants, even taking into account modernization, made it possible to create an intercontinental strategic bomner.
A specific implementation of the task in reference to the aircraft "85" was carried out for two types of engines. Initially in 1949, the first experienced engines of the ASh-2K were assembled and began to pass factory bench tests. In the second half of 1950, the Tu-4LL with the ASh-2K began to fly and carry out a program of tests and refinements of the new engine. These tests were delayed and passed in 1951, the engine overheated on tests and was not prepared in time for carrying out the State flight tests as part of the "85" aircraft. A long period of its refinement and refinement began. Because of this, the ASh-2K never got on the plane "85". The first "85/1" machine started flying with VD-4K and finished testing with it, the second "85/2" was to be tested with the AH-2K, but until the summer of 1951 the engine was never brought to normal and the "understudy" also flew off the VD-4K.
In November 1951, work on the aircraft began to wind down, by this time the ASh-2K could be put on a plane, but it lost its relevance in the new conditions. OKB AN Tupolev in the design of the "85" naturally made a bet on the ASh-2K, as its claimed data was higher than that of the VD-4K.
Installing the first machine engines m-253K did not stop the development of its alternative ASH-2 k. The Minister of aircraft industry M. Khrunichev wrote to Defense Minister n. Bulganinu: "As of 7th May, 1951 the M-253K has successfully passed State testing and flight tests on the plane, the Tu-4, gained on it for about 100 hours. The first TU-85 with Dobrynina motors also has more than 50 hours of flying time, including flying at a height of 10000 ft. By ASH-2 k ... technical difficulties, complexity, large amount of finishing works and elimination of defects on this motor prevented tonnes Švecovu to show it on the State tests in a timely manner.
"In order to ensure the timely transfer of second instance of the TU-85 the Government Commission on flight tests (June 1951-approx. com.), as well as in connection with the recent guidance on the preparations for the air parade of two TU-85, we organized the work on equipment and aircraft engines, the second copy of the m-253K.
"Based on the governmental AL-2 engine, which could be held in August this year, we will have converted one TU-85 Shvetsov engines and flight testing will be continued. Despite all the orders and regulations, the manufacturer's tests of the aeroplane continued to lag behind schedule. This contributed significantly to the unreliability of VD-4 k engines, especially at high altitude because of the surge of turbochargers. The plane itself was insufficient longitudinal stability and handling, which is not allowed to fly in adverse weather conditions."
The second type of engine was considered as a backup insurance, therefore, in considering the design, technical documentation and manufacturing of aircraft in their design, the possibility of using both types of engines was taken into account. The engine ASh-2K was a limited series until 1952, flying only in a flying laboratory. But it went down in the history of aircraft engine building as the most powerful piston engine implemented in the world, made in one unit. Manufactures of aircraft in their design took into account the possibility of using both types of engines.
In January 1949, the design bureau 36 offered on the basis of M-251 TC to create a new combined engine M-253 to the maximum power of 4300 hp in September 1949, a working project was completed and drawings of new units were developed: pulse turbines and turbocharger TC-36. In January 1950 the first engine was ready and in December 1950. The M-253 K together with TC-36 was presented on the state bench tests which it finished in the beginning of February 1951 with positive results. This confirmed full conformity of all parameters as well as the reliability of the design. At the end of the test M-253 received the designation 4k. In the second half of 1950, the 4k was installed on the Tu-4LL flying laboratory, where two engines of the WA-3TK had been tested.
By early 1951 the VD-4k with four turbochargers TC-36 and the Jet pipe passed bench tests. With a weight of 1930 pounds he developed the rated power of 3050 HP at sea level and 3250 HP at 10000 m, more than 1000 m above the height limit set by the Government. Total same takeoff power, taking into account the reaction of exhaust has 4300 HP, which is almost twice higher than that of the engine of the Tu-4 bomber. Fuel rate at sea level was at an all-time low 0.185-0.195 kg/BHP hour. With these motors the creation of an intercontinental bomber was quite a real prospect.
Finally, the 4k secured the aircraft "85" at the end of May 1951, when it was decided to raise "85" in the first flight with the WA-4k, as Al-2k was still suffering from "childhood illnesses". With the official completion of the program of creation of Tu-85, work on the 4k was gradually curtailed. Creation and flight tests of 4k became the pinnacle of development of piston aviation engine. For creation of the 4k group of employees of OKB-36 and CIAM was awarded in 1951 Stalin Prize.
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